Which chemical process is used to break and reform the bonds in hair?

The chemical process that is used to break and reform the bonds in hair is perming. This process involves the use of chemical solutions to break the disulfide bonds in the hair's structure, allowing the hair to be reshaped into curls or waves. After the bonds are broken, the hair is wrapped around curling rods and a neutralizer is applied, which reforms the disulfide bonds in the new shape. This ability to fundamentally change the hair's structure makes perming distinct from the other options, which do not involve altering the hair's curl pattern.

Relaxing focuses on straightening curly or wavy hair by breaking down the natural curl pattern, but it does not create curls as perming does. Coloring and bleaching are processes that alter the appearance of the hair by changing its color but do not involve breaking and reforming the structural bonds in the same way that perming does. Thus, perming is specifically designed to reshape hair through the chemical alteration of its bonds.